1. The Field of the Invention
This invention relates to signal processing and, more particularly, to novel systems and methods for pattern recognition and data interpretation.
2. The Background Art
Environmental data and stimuli have been the subject of much study for the purpose of organizing, interpreting and making useful for a future application the information that can be learned from the data.
Some sources of data that have captured the interest of those skilled in the art include neural functions. A neurocognitive adaptive computer interface method and system based on on-line measurement of the user's mental effort is described in U.S. Pat. No. 5,447,166. This method appears to be a neural network algorithm trained on data from a group of subjects performing a battery of tasks to estimate neurocognitive workload. It seems to represent a very specific algorithm trained on group data to estimate another very specific cognitive feature of brainwaves. It does not appear to be a general purpose method of analyzing all brain activity, nor does it appear to have broad application outside the tasks on which it was trained.
An electroencephalic neurofeedback apparatus for training and tracking of cognitive states is described in U.S. Pat. No. 5,406,957. This patent describes the basic invention of the mind mirror which is commercially available. The brainwave signal is Fast-Fourier-Transformed and the resulting frequency bands are displayed on a computer. The display and signal are used for biofeedback purposes but the signal is not classified or interpreted.
A brainwave directed amusement device was developed as described in U.S. Pat. No. 5,213,338 in a patent that details an arousal-level detection algorithm which is used to provide simple control of a video game. The algorithm measures the intensity (by amplitude) of raw brainwaves or a particular frequency band which varies in amplitude with the degree of arousal or relaxation a player experiences. This device is similar to other products on the market that use arousal-level to control a video game. The algorithm which provides this type of control appears limited to emotion-based arousal-level estimation and is correspondingly capable of only simple control through changes in the amplitude of one or two frequency bands from one or two sensor channels. These types of algorithms are typically limited to providing control based on brainwave arousal level or Galvanic Skin Response (GSR), also known as skin conductivity. This type of algorithm may provide a functional polygraph for lie detection and emotional arousal-level monitoring.
U.S. Pat. No. 5,392,210 concerns the localization or estimated reconstruction of current distributions given surface magnetic field and electric potential measurements for the purpose of locating the position of electrophysiological activities. The patent describes a method of getting closer to the source activity, but does not seem to provide a system of analysis or classification or interpretation of that source activity.
A method and device for interpreting concepts and conceptual thought from brainwave data and for assisting diagnosis of brainwave dysfunction is described in U.S. Pat. No. 5,392,788. This patent describes an analysis of Average Evoked Potentials by comparing the measured Evoked Potentials to the size and shapes of model waveforms or Normative Evoked Potentials, yielding from the comparison an interpretation. However, the system averages data, and requires an a priori model to be constructed for a diagnosis to be possible.